Eh, I believe in striking while the iron is hot; but I figure that if fanboys can (im)patiently wait 4 years between TDK and TDKR, they can do the same for the Avengers films. And yes, it would give more time to build up the MCU with new characters and sequels for the primaries.

True that, but at least we have the solo films inbetween unlike DC's films so far.